Nanowires can be useful in electronic and optical devices including integrated circuit interconnects, field effect transistors, photodetectors, biochemical sensors, light-emitting diodes, and complementary logic devices. Synthetic methods are known which do not rely on conventional lithographic techniques which yield silicon nanowires micrometers in length with diameters below 10 nm. The synthetic methods, however, are not necessarily commercially attractive. Thus, a need exists for a method for producing nanowires, including Group IV nanowires including silicon and germanium nanowires, which are of commercial interest. They should feature, for example, improved synthetic and morphological control and commercial production capabilities for providing high quantities of materials. In particular, a need exists for a method of producing nanowires which high quality: for example, they should be substantially straight and substantially free of corresponding nanoparticles, which can form along with the nanowires. In addition, material stability can be important, and surface passivation methods are also needed which are compatible with the nanowire synthesis.